PHP provides a comprehensive set of array functions for manipulating and working with arrays. Here's a list of important array functions:

1. Creating and Manipulating Arrays:

1. array() - Creates an array.

   • Example: $arr = array(1, 2, 3);

2. array_change_key_case() - Changes the case of all keys in an array.

   • Example: array_change_key_case($arr, CASE_UPPER);

3. array_chunk() - Splits an array into chunks.

   • Example: array_chunk([1, 2, 3, 4], 2);

4. array_column() - Returns the values from a single column in a multidimensional array.

   • Example: array_column($arr, 'column_name');

5. array_combine() - Creates an array by using one array for keys and another for values.

   • Example: array_combine($keys, $values);

6. array_count_values() - Counts all the values in an array.

   • Example: array_count_values($arr);

7. array_fill() - Fills an array with values.

   • Example: array_fill(0, 5, 'apple');

8. array_fill_keys() - Fills an array with values, specifying keys.

   • Example: array_fill_keys(['a', 'b', 'c'], 1);

9. array_filter() - Filters elements of an array using a callback function.

   • Example: array_filter($arr, 'is_even');

10. array_flip() - Exchanges all keys with their associated values.

    • Example: array_flip($arr);

2. Searching and Sorting Arrays:

11. array_key_exists() - Checks if a specified key exists in an array.

    • Example: array_key_exists('key', $arr);

12. array_keys() - Returns all or a subset of keys from an array.

    • Example: array_keys($arr);

13. array_merge() - Merges one or more arrays.

    • Example: array_merge($arr1, $arr2);

14. array_merge_recursive() - Recursively merges two or more arrays.

    • Example: array_merge_recursive($arr1, $arr2);

15. array_multisort() - Sorts multiple arrays or multidimensional arrays.

    • Example: array_multisort($arr1, SORT_ASC, $arr2, SORT_DESC);

16. array_pad() - Pads an array to a specified length with a value.

    • Example: array_pad($arr, 5, 'apple');

17. array_pop() - Pops the last element off the end of an array.

    • Example: array_pop($arr);

18. array_push() - Pushes one or more elements onto the end of an array.

    • Example: array_push($arr, 'value');

19. array_rand() - Picks one or more random keys from an array.

    • Example: array_rand($arr);

20. array_reduce() - Iteratively reduces an array to a single value using a callback.

    • Example: array_reduce($arr, 'sum');

21. array_replace() - Replaces elements from passed arrays into the first array.

    • Example: array_replace($arr1, $arr2);

22. array_reverse() - Returns an array with elements in reverse order.

    • Example: array_reverse($arr);

23. array_search() - Searches an array for a value and returns the corresponding key.

    • Example: array_search('needle', $arr);

24. array_shift() - Shifts the first element off an array.

    • Example: array_shift($arr);

25. array_slice() - Extracts a slice of the array.

    • Example: array_slice($arr, 2);

26. array_splice() - Removes a portion of the array and replaces it with something else.

    • Example: array_splice($arr, 2, 2, ['new_value']);

27. array_sum() - Returns the sum of values in an array.

    • Example: array_sum($arr);

28. array_unique() - Removes duplicate values from an array.

    • Example: array_unique($arr);

29. array_unshift() - Prepends one or more elements to the beginning of an array.

    • Example: array_unshift($arr, 'value');

30. array_values() - Returns all the values of an array.

    • Example: array_values($arr);

31. arsort() - Sorts an array in reverse order, preserving key associations.

    • Example: arsort($arr);

32. asort() - Sorts an array and maintains index association.

    • Example: asort($arr);

33. krsort() - Sorts an array by key in reverse order.

    • Example: krsort($arr);

34. ksort() - Sorts an array by key in ascending order.

    • Example: ksort($arr);

35. rsort() - Sorts an array in reverse order.

    • Example: rsort($arr);

36. sort() - Sorts an array in ascending order.

    • Example: sort($arr);

3. Array Mapping and Manipulation:

37. array_map() - Applies a callback to the elements of an array.

    • Example: array_map('strtoupper', $arr);

38. array_walk() - Applies a user-defined function to each element of an array.

    • Example: array_walk($arr, 'my_function');

39. array_walk_recursive() - Applies a user-defined function to each element of a multidimensional array.

    • Example: array_walk_recursive($arr, 'my_function');

40. array_product() - Calculates the product of values in an array.

    • Example: array_product($arr);

41. array_intersect() - Computes the intersection of arrays.

    • Example: array_intersect($arr1, $arr2);

42. array_intersect_assoc() - Computes the intersection of arrays with additional index check.

    • Example: array_intersect_assoc($arr1, $arr2);

43. array_intersect_key() - Computes the intersection of arrays using keys for comparison.

    • Example: array_intersect_key($arr1, $arr2);

44. array_diff() - Computes the difference of arrays.

    • Example: array_diff($arr1, $arr2);

45. array_diff_assoc() - Computes the difference of arrays with additional index check.

    • Example: array_diff_assoc($arr1, $arr2);

46. array_diff_key() - Computes the difference of arrays using keys for comparison.

    • Example: array_diff_key($arr1, $arr2);

4. Other Array Functions:

47. array_replace_recursive() - Recursively replaces elements from passed arrays into the first array.

    • Example: array_replace_recursive($arr1, $arr2);

48. array_key_first() - Gets the first key of an array.

    • Example: array_key_first($arr);

49. array_key_last() - Gets the last key of an array.

    • Example: array_key_last($arr);

50. array_combine() - Creates an array by using one array for keys and another for values.

    • Example: array_combine($keys, $values);

These array functions in PHP allow for versatile and powerful manipulation of arrays, helping to handle a wide variety of data-processing tasks. Whether you need to sort, filter, search, or modify arrays, PHP provides a vast toolkit to meet your needs.